Project summary About 1/3rd of people with epilepsy are medically refractory, that is, do not achieve seizure freedom with antiepileptic drugs (AEDs). There are few evidence-based guidelines on the optimal treatment of refractory patients. In previous work, we studied an institutionalized, developmentally disabled patient population in Washington State and discovered that of the most frequently-used AED regimens, only the combination of lamotrigine (LTG) and valproate (VPA) demonstrated significant benefit in refractory epilepsy. A caveat to this finding was the specialized patient population in which the study was conducted. In this proposal, we will use two complementary approaches in community-based patients to search for AED regimens with superior efficacy in refractory patients, so to determine whether our previous findings are applicable to the general refractory epilepsy population. In the first Specific Aim, we will study individuals with epilepsy who use either of two online seizure diaries to track their seizure occurrences and AED usage. In the second Aim, we also study the entire outpatient epilepsy population of the University of Washington Regional Epilepsy Center, using automated analysis of the electronic health record, to determine which AED regimens had the highest success rate in producing seizure freedom. The potential outcome of this study will be the identification of AED regimens that are the most effective in a prevalent but difficult to treat epilepsy population.